Bài giảng what is biodiversity

What is Biodiversity?


Biodiversity is:
the variety of life on Earth at all its levels,
from genes to ecosystems, and the ecological
and evolutionary
processes that sustain it.

Source: ©AMNH-CBC


Dimensions of biodiversity
Genetic
component

Spatial
component

Functional
component

Temporal
component

within individuals

communities

daily

within
populations

ecosystems

e.g. reproductive
behavior,
predation,
parasitism

between
populations
between species

seasonal

landscapes

annual

ecoregions

geological or
evolutionary

biogeographic
regions


Hierarchy of Biodiversity

Ecological
diversity
Biomes
Bioregions
Landscapes
Ecosystems
Habitats
Niches
Population

Organismal
diversity
Phyla
Classes
Orders
Families
Genera
Species
Subspecies
Population
Individuals

Genetic
diversity
Population
Individuals
Chromosomes
Genes
Nucleotides

Source: Yves Samyn


Hierarchy of
Biodiversity

Elements of biodiversity form nested hierarchies
Source: Yves Samyn


Genetic Diversity
The variation in the
nucleotides, genes,
chromosomes, or
whole genomes of
organisms
Source: Human Genome Project, Department of Energy


Variation in genome size

Source: U.S. Dept. of Energy, Human Genome Project
/>
A greater total number of genes
might not correspond with a
greater complexity in the
anatomy and physiology of
the organism

Species

Organism
common name

Number of genes
in genome

Reference

Arabidopsis
thaliana

thale cress

25,498

Oryza sativa
(indica-cultivar
subgroup)
Caenorhabditis
elegans

Indian rice

46,022-55,615

Arabidopsis
Genome Initiative
(2000)
Yu et al. (2002)

nematode

 19,000

Drosophila
melanogaster

fruit fly

13,600

Homo sapiens

human

ca. 30,000-40,000

C. elegans
Sequencing
Consortium
(1998)
Adams et al.
(2000)
International
Human Genome
Sequencing
Consortium
(2001)

Phenotypic Diversity
Phenotype - the physical constitution of an organism that
results from its genetic constitution (genotype) and the
action of the environment on the expression of the genes.
Thus, phenotypic
diversity refers to
variation in the
physical traits of the
organism.

Domroese ©AMNH-CBC


An Example of Genetic Variation

Source: ©AMNH-CBC


Morphological diversity within and
between natural populations: An example


Morphological diversity within and between
natural populations: Vietnam’s examples

Nguyen et al. 2009


A population is:

• a group of individuals of the same species that share
aspects of their genetics or demography more closely with
each other than with other groups of individuals of that
species

• a more practical way of defining a population and
measuring its diversity is by the space it occupies. Thus a
population may be defined as a group of individuals of
the same species occupying a defined area at the same
time (Hunter, 2002).


Cryptic Species
• taxonomically cryptic
species look very
similar to other species
• may be misidentified
(and hence overlooked
as being a different
species).
Source: Bain ©AMNH-CBC


Population Diversity
• Variation in the quantitative and spatial
characteristics between populations


Proportion of total genetic variation within
species due to genetic differences between

geographic populations (from Avise, 1994)
Group
Mammals
Birds
Reptiles
Amphibians
Fishes
Insects
Crustaceans
Mollusks

Population Differences
0.242
0.076
0.258
0.315
0.135
0.097
0.169
0.263


Importance of population
variation
Loss of isolated populations along with
their unique component of genetic
variation is considered by some scientists
to be one of the greatest but most
overlooked tragedies of the biodiversity
crisis.

Species concepts
• Morphological
• Biological
• Phylogenetic
– Each definition of species produces a different
count of species.
– Therefore, each definition has a different effect
on how we plan conservation.


Species diversity vs. richness
•Species richness: the number of species present in a given area

• Species diversity: species number weighted by measure of importance, such as
abundance, productivity or size
For example:
Shannon’s diversity index (H) = -i ln i
i is the proportion of the total number of specimens of species i expressed
as a proportion of the total number of specimens for all species in the
ecosystem.
Many people use the term “species diversity” when they mean species richness


RICHNESS vs. EVENNESS
250

Ecosystem A
SR = 4

H' = 1.3086
SE = 0.94

Ecosystem B

Ecosystem C

SR = 3
H' = 1.0807
SE = 0.98

SR = 3
H' = 1.0323
SE = 0.94

# Individuals of Each Species

200

150
Spe cie s 1
Spe cie s 2
Spe cie s 3
Spe cie s 4
100

50

0
Ecosystem

Adapted from: Hunter, M. Jr. 2002. Fundamentals of Conservation
Biology. Second Edition. Blackwell Science, Massachusetts, U.S.A.


Developing this idea further
• An ecosystem with representative species from
many different higher taxa present (e.g from
different families or orders) possess more
taxonomic or phylogenetic diversity than
another with fewer higher taxa but many more
species.
• Marine ecosystems frequently have more
different phyla but fewer species than
terrestrial ecosystems; i.e. higher taxonomic
diversity but lower species diversity.


Community Diversity
• Variation in the groups of populations
and species that share an environment


Ecosystem Diversity
• An ecosystem is a community plus the physical
environment that it occupies at a given time.


Some examples of ecosystems
–

–
–
–
–

coral reefs
tallgrass prairie
coastal wetlands
old-growth forest
tropical rainforest

Mangroves,
Belize

Source: Harrison ©AMNH
Source: Brumbaugh ©AMNH-CBC


Inter-species interactions
underpin ecosystem diversity
• There are very many potential interactions among
species, such as:
– predation,
– competition,
– parasitism,

– mutualism

• Some of these involve very close ecological and
evolutionary associations between the organisms and

are an important component of community and
ecosystem biodiversity
– consider for example plant pollinators and seed dispersers


Examples of distinct
communities and ecosystems
• Species associated with:
ripening figs in a tropical
forest,
• Species clustered around
a hydrothermal vent on
the ocean floor,
• Species in the spray zone
of a waterfall,
Source: ©AMNH

• Species under warm
stones in the alpine zone
on a mountaintop.